As we know, the electric products have a tendency to become smaller in volume for a convenient portability. A notebook computer is getting more and more popular due to its small volume, portability and multifunctionality. There is a rechargeable battery provided for the notebook computer so that the notebook computer can be used in any place. However, a rechargeable battery can only store a limited electric capacity, i.e. a limited amount of charges. Hence, the user needs to know the residual electric capacity of the rechargeable battery in order to prepare previously before the electric capacity of the rechargeable battery is run out.
Please refer to FIG. 1 showing a schematic diagram of a general device for determining the residual electric capacity of the rechargeable battery. As shown in FIG. 1, the current gauge 11 is a BQ2040 gas gauge board. The current gauge 11 counts the input electric charges and output electric charges charged and discharged between the notebook computer 12 and the rechargeable battery 10 by using a counter, calculates the residual capacity of the rechargeable battery, and then show the counted electric capacity on the display through the notebook computer 12.
However, the current gauge 11 needs to be calibrated by executing a battery learning before being used. The process is simply described as follows. Firstly, the rechargeable battery 10 needs to be charged until the rechargeable battery 10 approaches a first saturation state. Secondly, the rechargeable battery 10 is discharged and the current gauge 11 counts the electric capacity discharged from the rechargeable battery 10. When the rechargeable battery 10 approaches a predetermined minimum capacity condition (a preset lowest residual electric capacity stored in the rechargeable battery 10 corresponding to a lowest voltage value (EDV1) recorded in an electrically erasable programmable readonly memory EEPROM of the current gauge 11 and the lowest capacity of the rechargeable battery 10, such as 2% of the total capacity), the user needs to zero the current gauge 11 and then recharges the rechargeable battery 10. After the rechargeable battery 10 is recharged, it is discharged and a counter of the current gauge 11 starts to count down according to the current charges output from the rechargeable battery 10. When the voltage reaches lowest voltage value (EDV1), the user needs to stop discharging the rechargeable battery 10 and records the electric capacity A counted by the current gauge 11. Finally, the rechargeable battery 10 is recharged. When the count counted down exceeds a specific value (for example 256), that the recharging process and the A value is correct is confirmed. Then, the battery learning ends.
The new total capacity of the rechargeable battery can be calculated according to the A value and the specific discharge condition by the following equation:
The new total capacity of the rechargeable battery=A+2% of the previous total capacity of the rechargeable battery.
Therefore, during the production process of the notebook computer, each of the rechargeable batteries mounted in the notebook computers needs to be executed a battery learning before the notebook computers are sold to customer. Please refer to FIG. 2 showing a general device for executing a battery learning process. A plurality of the notebook computers (211 . . . , and 21n) are electrically connected to a power source 22 through a switch 23 at the same time. Thereafter, the user turns on the switch 23 manually to charge the rechargeable batteries mounted in the notebook computers (211 . . . , and 21n). However, each of the rechargeable batteries mounted in the notebook computers has a different residual electric capacity. Hence, the user needs to charge all of the rechargeable batteries mounted in the notebook computers for a longer time in order to insure that each of the rechargeable batteries is in a saturation state. Then, the user turns off the switch 23 manually to discharge the rechargeable batteries mounted in the notebook computers. Certainly, it also costs the user a lot of time to discharge the rechargeable batteries in order to insure that the residual electric capacity stored in each of the rechargeable batteries is in a lowest state and the discharging process is completed.
However, by the above-described method and device, it may cost the user a lot of time to execute a battery learning process resulting in a low production efficiency. Moreover, the general method and device for executing a battery learning is very complex so that the user may not actually execute the learning in the production process. Besides, there may be an error value counted by the current gauge due to the wrong process. As we know, the total capacity of the rechargeable battery may decrease after a long time use. Hence, the current gauge needs to be calibrated by executing a battery learning process. However, the user needs to charge and discharge the rechargeable battery manually, and it must cost the user many hours to execute the battery learning process again.
Moreover, a nickel-hydrogen battery applied in those notebook computers usually has a defect of the memory effect. Hence, the rechargeable battery mounted in the notebook computer needs to be executed battery learning processes no less than three times to eliminate the memory effect before the notebook computer are sold. However, the required implement for achieving the purpose is to make tester to invest. It may bring about an increased manufacturing cost. Therefore, it is desirable to develop a method to solve the problems encountered by prior arts.